Their hydkolytic products



Patented Sept. 25, 1951 UNITED STATES? PATENT v, v ..2*,5"c9',i14 i 1 METHoD'oF PRODUCING LAc'rAMsAND 'rncrn HYnRoLYTIc PRODUCTS Alois'Novdtriy; fragile, slcvakia NcDrsv-ving: Application Asia 5; 1948; serial No;

19,1 75? In Ozechoslovakia September 8;- 1947 best prior art meth d of producinglactarns,

consisted in the rearrangement of cyclic oxilnes- 1111a, concentrated sulphuric acid solution at ele-.-

vatedtemperatures. This reaction is highly ex other 'nic; thereby necessitating specialmeasures for its control. The cyclic oximes maybeprepared from ketones by reacting them with hydroxylaminedisulfonicsalts or with hydrox yl amine salts. These oximes must be isolated in a," pure-form. carefully dried and cautiously. dissolved in sulphuric acid. Applicant has therefore developed amethod of; producing lactams, startingdirectly from cyclic ketones,- hydroxylamine sulphate and, sulphuricor turningsulphuric acid;

without isolating the intermediate cxime y. droxylaminesulphate, however, is relatively expensive; for industrial purposes.- I

alnmoniainthe presence of dehydratin anddehydrogenating; agentsnor the method-starting from- 5-valero1actamgives quite satisfactory results. These known methodsyield considerable amounts'of secondary products.

.7 It has now been found that it is possible to produce lactams in a very advantageous man-Q nerby-reacting mononitro-parafiins with cyclic ketones at elevated temperatures in the presence ofhydratesof sulphur trioxide, such as sulphuric or fuming sulphuric acid. Themononitroparair can be prepared in a cheap-and: easy way. The-reaction may becarried out in difiercnt ways One of the methods comprises the addition of boththe mononitroparaffin andthe cyclic ketone simultaneouslyand progressively into a preheated; sulphuric or fuming sulphuric acid solutiqn. This method can be made continuousbywith; drawing the reaction products continuously from;

areaction kettle which may be heated-or cooled; as needed, and simultaneously adding the cyclic ketone, nitroparafiinand sulphuric or fuming sulphnr'ic acid at another place of the said kettle.-- 'Ifhe lactam can be isolated fromthe-resul'ting acid solution in anyknown" manner, such; as;by

separating it by means of salts after neutralisa-;; tionc Another method consistsin an extractionof' the; neutrali'zedsolution by means of; organic solvents. TIFheraw product can be purifiedby means of; distillation in vacuo. If, instead of lactams their hydrolytic' products, such as the w-aminocarboxylic acidshave to be prepared, the: acid lacta n solution is dilutedwith'water. and boiled;

the; S04 thereby precipitating and the filtrate concentrated by evaporation. In order to-eIi mi-j mate thevolatile impurities, the solution is boiled finally in theabsenceof a-reflux coolerandthe} a can- N ither the'reaction' of dicar boxylic acids; with remaining. impurities are eliminated neutralisation by extracting with; a-solvent, such as be zene.-

,It is} known that the concentratedhydrochlo acid reaflis with nitroparaffins, yieldinghydroxyl aminehydrochloride and the corresponding iattil acidor its decomposition products respectively VQMeyer and P'; Jacobsohn, Lehrb uch der o ganischen- Chemie, I, 104-406) In the same pub-g lication however,-I find a statement that conce'n; trfl'tfid; sulphuric acid reacts in most cases; with nitroparafiins in a complicated manner. thermore it is known from; clsewhere- ()7.- Meyer A- 171-, 53) that fuming sulphuric acid-reacts with nitroethane to. yield ethanedisulphonic acid Previously, the nitromethane only was knowntabe decomposed by fuming sulphuric acid to form carbon monoxide and hydroxylaminesulphate. Inall other cases the' sulphuric-acid reacted with nitrocompounds at elevated temperaturesto produce complicated mixtures of different com; pounds; such" asnitrosulphonic carboxylic acids andsulphonatediatty acids etcv 7 It is therefore rathersurprising that difierent' nitrohydrocarbons yield lactams almost quaint-is:

' tatively; when heated with cyclic ketones in the;

presence of hydrates of; sulphur tri-oxide. It is; preferable to add the cyclic ketone simultaneously with. the nitroparaffin in order: to bind-"the formedhydroxylamine and tovchange the reaction equi -r; libriumcontinuously, promoting thusthe forma-, tion of the lactam. It is however possible to' use a. tw o step method; adding first the nitrocompound to the sulphuric acid; solution and then the ketone- Generally however this-method less-desirable; causin in some cases decreased yieldsofthe lactam. I V I 1 L 4 his .invention utilizes primary nitroparafiins} havingthegeneral formula RxCHaNOz gree of concentration of the sulphuric or fuming sulphuric acid'solution. The mixture is added" with stirring to the preheated, previously reacted mixture, prepared by a cautious heating of a small amount of the original .mixture.;; The

. What is claimed by Letters Patent is:

produced surplus heat must be dissipated. :It is -1.

also possible to direct the cold or the preheated mixture through a reaction zone heated to the reaction temperature in such amanner-thatonly a small amount of the reactants are present/a.

within said zone, thereby affording a simple and eflicient means of dissipating the surplus reaction heat.

further embodimentof the invention-comsists'in spraying the mixture into-a preheated space, containing inert gases or vapours, and drawing off the reaction liquid which, condenses on the cooled walls. The cooling must not be so severe as to interfere with the reaction. If the reaction space is filled with superheated steam Whichmay also function as a heating means, it is possible to directly carry out the hydrolysis of the lactam solution to form the respective w-aminoacid in dilute sulphuric acid. The preheated steampressure may also serve directly for spraying the mixture. The invention is additionally illustrated by the following-examples, but are not to be constrained aslimiting the scope thereof.

. Erampl e 1 500 parts of concentrated sulphuric acid'are mixed with 305 parts of nitromethane (boilingpoint 98-101 C.) in a vessel, provided with a reflux cooler. The vessel is placed into a heatin bath, previously heated up to 123 C. After 10 minutes, the bath temperature being 120 C., 440 parts of cyclohexanone (90%) is slowly added. At first vapors distilled and returned by r'eflux into the vessel. After a short period of time the reflux stopped. Then the mixture was heated for 5-more minutes at a temperature of 1'20-125 C. After cooling, the mixture was poured slowly into aqueous ammonia, thus preventing the temperature from rising above 36 C. The final reaction was weaklyalkaline. After standing for a while, the oily upper layer in an amount of 500 parts was separated and distilled in vacuo. The yield of pure S-caprolactam (B. P. l38-l39 C. at 8-9 mm. Hg) a yield of 78.9%. based on the amount of cyclohexanone used was 360 parts.

Emample 2 velocity in order to maintain the temperature be low 120 C. The mixture was continuously withdrawn from the vessel through a long tube, sub

merged ina bath, having a temperature of 125- 1-30" C., the cold concentrated sulphuric-acid be-' ing supplied simultaneously into --the reaction vessel. The supply of the nitroparaflin-cyclohexanone mixture was regulated by means of a sensitive thermostat in order to accommodate the supply to the efliciency of the reflux cooler. The lactam was isolated from the reaction mixture by the same means as described in Example 1, a yield greater than 90% of the theoretical was obtained. The aqueous mother liquor contained different fatty acids which can be isolated in any known manner.

.:1. A method of producing lactams and fatty acids simultaneously which comprises reacting primary nitroalkanes having more than one carbon atom with an alicyclic mono-ketone in the presence of a sulfur trioxide hydrate at a temperature. up to about 160 C., separating the .lactam from the fatty acid, and recovering the lactam and the fatty acid.

2. A continuous method of producing lactams and fatty acids simultaneously which comprises introducing concurrently primary nitroalkanes having more than one carbon atom and ali-' cyclic mono-ketones into a preheated solution of sulfur trioxide hydrate, maintaining the reaction mixture at a maximum temperature of about C., continuously withdrawing the reaction products consisting essentially of lactams and fatty acids, separating the lactams from the fatty acids, and recovering the lactams and the fatty acids. I

3. A method of producing lactams and fatty acids simultaneously which comprises introduc-- ing concurrently primary nitroalkanes having more than one carbon atom and alicyclic monoketones into a preheated solution of sulfur trioxide hydrate, maintaining the reaction mixtureat amaximum temperature of about 160 C., separating said lactam from said fatty acids,

and recovering the lactams and the fatty acids. '4. A method of producing lactams and fattycyclic mono-ketones in the presence of sulfur trioxide hydrates at a maximum temperature of about 160 C., and recovering said lactams.

6. A method of producing substantially pure lactams which comprises introducing an alicyclic mono-ketone into a preheated mixture of primary nitroalkanes and sulfur trioxide hydrates, cooling the reaction mixture to a maximum temperature of about 160 C., and recovering a lactam.

7. A method of producing substantially pure fi-caprolactam which comprises introducing cyclohexanone into a preheated mixture of nitromethane and concentrated sulfuric acid, cooling the reaction mixture to a maximum temperature of about 160 C., and recovering 6-caprolactam.

8. A method of producing lactams and fatty acids simultaneously which comprises reactinga mixture of low molecular primary nitroalkanes with cyclohexanone in the presence of a concentrated sulfuric acid at a temperature up to about 160 C., separating the lactam from the fatty acid, and recovering the lactam and thefatty acid.

- 9. A method of producing 5 a mixture comprising primary nitroalkanes containing more than 1 carbon atom, an alicyclic mono-ketone and sulfur trioxide hydrates into an inert medium maintained at a maximum temperature of about 160 0., collecting the reaction products, separating and recovering said lactams and fatty acids.

ALOIS NOVOTNY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name FOREIGN PATENTS Country Date Switzerland Aug. 1, 1945 Number Preibisch, Jour. Prakt. Chem. (115) (1873) p. 480.

Moncrieff, Manufacturing Chemist and Manufacturing Perfumer, vol. XVII (June, 1946) p. 

1. A METHOD OF PRODUCING LACTAMS AND FATTY ACIDS SIMULTANEOUSLY WHICH COMPRISES REACTING PRIMARY NITROALKANES HAVING MORE THAN ONE CARBON ATOM WITH AN ALICYCLIC MONO-KETONE IN THE PRESENCE OF A SULFUR TRIOXIDE HYDRATE AT A TEMPERATURE UP TO ABOUT 160* C., SEPARATING THE LACTAM FROM THE FATTY ACID, AND RECOVERING THE LACTAM AND THE FATTY ACID. 